Analog Devices Inc. AD977ACR

Overview

AD977ACR from Analog Devices is a 16-bit, 200 kSPS successive-approximation analog-to-digital converter (ADC) operating from a single 5 V supply. It features internal 2.5 V reference, high-speed serial interface, on-chip clock, and supports ±10 V, ±5 V, and ±3.3 V bipolar input ranges - used in precision industrial data acquisition systems requiring high linearity and low power.

For engineers reviewing the AD977ACR datasheet, AD977ACR pinout, AD977ACR application, or AD977ACR equivalent, key selection considerations include throughput rate (200 kSPS), integral nonlinearity (±3 LSB), full-power bandwidth (1 MHz), power-down mode (50 µW), and compatibility with external or internal reference configurations.

Technical Context

The AD977ACR implements a factory-calibrated switched-capacitor SAR architecture with integrated reference buffer and serial output stage. Its conversion control relies on dual digital inputs (R/C and CS), supporting both internal clock–driven and externally synchronized readout modes via EXT/INT and DATACLK pins.

It delivers dc accuracy including ±3 LSB INL and ±0.5% full-scale error, plus ac performance of 83 dB SNR and 90 dB SFDR at 20 kHz input. The device supports binary two's complement or straight binary output coding, selectable via SB/BTC pin, and recovers to rated accuracy within 1 ms after power-down.

Key Specifications

Pinout & Package

AD977ACR is housed in a 20-lead skinny SOIC (SOIC_N) package with exposed pad not present; thermal resistance θ_JA = 75°C/W. Pin functions are validated per Analog Devices Rev. E datasheet Figures 3 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with AD7606BCPZ and ADS8860IDRCT, the AD977ACR uniquely balances single-channel precision, self-contained reference, low power-down consumption, and compact SOIC packaging - making it ideal for cost-sensitive, space-limited, or low-duty-cycle instrumentation where multi-channel or ultra-high speed is unnecessary.

Availability

AD977ACR is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, medical instrumentation, and energy metering applications requiring stable component supply and long-term obsolescence management.

Supply support for AD977ACR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD977 family belongs to Analog Devices' precision data acquisition product line, designed specifically for high-resolution, low-power, single-channel industrial and instrumentation applications where accuracy, reliability, and ease of integration are prioritized over channel count or extreme speed.

FAQ

What is the maximum sampling rate supported by the AD977ACR?

The AD977ACR supports a maximum throughput rate of 200 kSPS, corresponding to a complete conversion cycle time of 5 µs. This is confirmed in Table 2 of the Rev. E datasheet under "AD977A–Specifications" and applies to all grade versions (A/B/C) across the –40°C to +85°C temperature range. The AD977ACR achieves this using a factory-calibrated successive approximation register (SAR) architecture with on-chip clock generation.

Does the AD977ACR require an external reference voltage?

No, the AD977ACR does not require an external reference voltage. It integrates a precision 2.5 V internal reference (2.48 V to 2.52 V, ±0.2% initial accuracy) that can be used directly. However, an external reference between 2.3 V and 2.7 V may be applied to REF for improved accuracy or system-level reference sharing. The internal reference is enabled by default unless overridden via the REF pin.

What package type is used for the AD977ACR?

The AD977ACR is packaged in a 20-lead skinny SOIC (SOIC_N) package, as specified in the Ordering Guide and confirmed in Figure 3 and Table 6 of the Rev. E datasheet. This package has standard 0.3-inch body width and 0.050-inch lead pitch. It is distinct from the 28-lead SSOP variant (AD977ARS) and does not include a thermal pad.

How does the power-down mode function on the AD977ACR?

The AD977ACR enters power-down mode when the PWRD pin is driven logic HIGH, reducing supply current to 50 µW while retaining the last conversion result in its internal shift register. Power-down recovery time is 1 ms when a 2.2 µF capacitor is connected to CAP, as specified in Table 2. During power-down, conversions are inhibited but the device remains responsive to control signals for rapid wake-up.

Can the AD977ACR interface directly with a microcontroller SPI port?

The AD977ACR supports serial data output synchronized to either an internal clock (via DATACLK pin) or an external clock, but it does not implement a standard SPI protocol (no dedicated MOSI/MISO/SS lines or frame formatting). Microcontrollers must bit-bang the interface using R/C, CS, BUSY, and DATACLK timing per Figures 6–12. Data is MSB-first, valid on both edges of DATACLK in internal mode, and requires careful timing alignment in external mode.